JP2003103637A - Method for connecting composite high-pressure pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To tightly connect composite high-pressure pipes excellent in pressure resistance to each other by butt fusion and to simplify connection work. SOLUTION: While the end of each high-pressure pipe 1 and 1, for example, is heat-melted under conditions of a heating temperature of 210-260 deg.C and heating time of 90-250 s, the ends of the pipes are butted together by a pressure (e.g. 0.15 MPa) which is higher than a usual butt-fusion temperature to make a molten resin of an inner layer end flow outside through the gap between oriented polyolefin resin sheets of a butt part to fusion-bond the ends of the inner layers to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of connecting composite high-pressure pipes for connecting composite high-pressure pipes used for flowing and transporting various substances.

[0002]

2. Description of the Related Art Pipes such as pipes and hoses used for transporting various substances such as liquids and gases by flowing are required to have pressure resistance so as not to be damaged by the pressure of the substances flowing inside. . In particular, when carrying a high-pressure fluid such as oil resistant pipes and water supply pipes, high pressure resistance is required. As a tubular body having pressure resistance, for example, Japanese Patent Application Laid-Open No. 8-11250
Japanese Patent Laid-Open Publication proposes a composite high-pressure pipe with increased pressure resistance by providing a fiber reinforced layer and a wire reinforced layer between an inner layer and an outer layer formed in a tubular shape from a flexible material such as synthetic resin. There is.

[0003]

By the way, in the above-described composite high-pressure pipe, the fiber reinforcing layer provided between the inner layer and the outer layer is formed by braiding fibers having an appropriate thickness or winding the fibers in a spiral shape. Since they are arranged, there is a problem that the fiber reinforcing layer itself becomes thick. Further, the fiber-reinforced layer formed by bundling the fibers has a problem that the axial strength along the longitudinal direction of each fiber is greater than the strength in the circumferential direction.

Moreover, since the wire reinforcing layer is laminated on the fiber reinforcing layer, the overall wall thickness becomes thicker and the total weight becomes heavier, which makes the handling difficult and the economical efficiency worse. is there.

Furthermore, since the inner layer and the outer layer made of synthetic resin are different from the material of the fiber reinforcing layer and the wire reinforcing layer, the composite high-pressure pipes to be connected cannot be directly joined. For this reason, for example, using pipe fittings,
Although it is necessary to connect the composite high-pressure pipes to each other, when a pipe joint is used, the strength and sealing property of the connecting portion between the pipe joint and the composite high-pressure pipe become problems. Therefore, although the composite high-pressure pipe having excellent pressure resistance is used, the piping may cause damage or water leakage at the connection between the composite high-pressure pipes.

On the other hand, when the tubes are connected by butt fusion welding, as a method for preventing the destruction of the butt fusion welding portion when an internal pressure is applied, for example, as disclosed in JP-A-11-101383, fusion is performed. There is a method of fixing the outside of the attachment part with a reactive resin. In this method, after butt fusion, a die is attached to the fusion zone, and a reactive resin is poured into a gap between the tube and the die to solidify the resin for reinforcement.

However, in such a reinforcing method, since a reactive resin, which requires careful handling, is used,
It cannot be said that this is an easy method in terms of construction, since the mold must be removed after the resin has solidified. further,
Since the solidified reactive resin is hard, there is a problem that the composite high-pressure pipe is easily broken when flattened.

The present invention has been made in view of such an actual situation, and in connecting composite high-pressure pipes having excellent pressure resistance by butt fusion welding, the composite high-pressure pipes are firmly connected to each other by simple work. An object of the present invention is to provide a method of connecting a composite high-pressure pipe, which is capable of forming a flexible connection portion that can follow the deformation of the composite high-pressure pipe.

[0009]

The connection method of the present invention is formed by spirally winding an inner layer made of synthetic resin in a tubular shape and an outer peripheral surface of the inner layer with a stretched polyolefin resin sheet. A method of connecting the ends of a composite high-pressure pipe having a reinforcing layer and an outer layer made of synthetic resin laminated on the reinforcing layer by butt-joining each other, and heating and melting the end of each composite high-pressure pipe. , The ends of each composite high-pressure pipe,
It is characterized by fusing the ends of the inner layer by abutting the molten resin at the ends of the inner layer with a pressing force such that the molten resin flows outward through the stretched polyolefin-based resin sheets at the abutting portions.

In the connection method of the present invention, when connecting the composite high-pressure pipes whose inner layer is formed of high-density polyethylene, the end of each composite high-pressure pipe is heated at a heating temperature of 210 to 260.
C., heating time: heated and melted under the conditions of 90 to 250 sec, and melted length of inner layer end (melted length from pipe end face)
Is preferably longer than in the case of normal connection.
In this case, the melting length of the inner layer end varies depending on the diameter of the composite high-pressure pipe to be connected, but for example, a small diameter (nominal diameter 30
In the case of a tube up to 0 A), it is preferably about 1.0 to 1.5 times the inner layer wall thickness.

In the connection method of the present invention, it is preferable that the end portions of the composite high-pressure pipe are butt-welded together with a pressure of 0.1 to 0.2 MPa.

The connection method of the present invention has a synthetic resin inner layer formed in a tubular shape, and a reinforcing layer formed by spirally winding a stretched polyolefin resin sheet on the outer peripheral surface of the inner layer. A method for butt-connecting end portions of a composite high-pressure pipe (two-layer structure), wherein the end portions of each composite high-pressure pipe are heated and melted, It is characterized in that the ends of the inner layer are fused by abutting with a pressing force such that the molten resin flows outward through the stretched polyolefin-based resin sheets at the abutting portions.

In the connecting method of the present invention, when connecting the composite high-pressure pipes whose inner layers are formed of high-density polyethylene, the end of each composite high-pressure pipe is heated at a heating temperature of 210 to 260.
C., heating time: heated and melted under the conditions of 90 to 250 sec, and melted length of inner layer end (melted length from pipe end face)
Is preferably longer than in the case of normal connection.
In this case, the melting length of the inner layer end varies depending on the diameter of the composite high-pressure pipe to be connected, but for example, a small diameter (nominal diameter 30
In the case of a tube up to 0 A), it is preferably about 1.0 to 1.5 times the inner layer wall thickness.

In the connection method of the present invention, it is preferable that the end portions of the composite high-pressure pipe are butt-welded together with a pressure of 0.1 to 0.2 MPa.

Next, the composite high-pressure pipe to which the connecting method of the present invention is applied will be described in detail.

First, the stretched polyolefin resin sheet constituting the reinforcing layer of the composite high-pressure pipe will be described.

The stretched polyolefin-based resin sheet refers to a sheet composed of a material containing a polyolefin-based resin as a main component, which is stretched in at least the longitudinal direction.

The polyolefin resin is not particularly limited, and examples thereof include low density polyethylene, linear low density polyethylene, high density polyethylene, homopolypropylene, propylene random copolymer, propylene block copolymer and poly. (4-methyl-1-pentene) and the like. Of these polyolefin resins,
Polyethylene having a high elastic modulus after stretching, particularly high-density polyethylene having high crystallinity, is preferable.

If necessary, a crystal nucleating agent, a cross-linking agent, a cross-linking aid, a lubricant, a filler, a pigment, a different kind of polyolefin-based resin, a low-molecular-weight polyolefin wax or the like may be added to the polyolefin-based resin.

The crystal nucleating agent is added for the purpose of improving the crystallinity, and examples thereof include calcium carbonate and titanium oxide.

The cross-linking agent and the cross-linking aid are added for the purpose of partially cross-linking the molecular chains of the above polyolefin resin to improve the heat resistance and creep performance of the stretched polyolefin resin sheet. Examples of the crosslinking agent include photopolymerization initiators such as benzophenone, thioxanthone, and acetophenone. Examples of the crosslinking aid include polyfunctional monomers such as triallyl cyanurate, trimethylolpropane triacrylate and diallyl phthalate.

Instead of using the above-mentioned crosslinking agent, a crosslinking means by electron beam irradiation or ultraviolet irradiation may be adopted.

For the crosslinking means by electron beam irradiation or ultraviolet ray irradiation, is added the above-mentioned crosslinking agent or crosslinking auxiliary agent to the polyolefin resin, and is preferably irradiated with an electron beam of 1 to 20 Mrad, more preferably 3 to 10 Mrad. Alternatively, preferably 50 to 800 mW / cm ² , more preferably 1
A method of irradiating with an ultraviolet ray of 0 to 500 mW / cm ² can be mentioned. Such a cross-linking step may be performed at the same time as the later-described stretching step or subsequent to the stretching step.

By cross-linking by the above method,
Since the creep performance of the stretched polyolefin-based resin sheet is improved and the creep performance with respect to the internal pressure when using the composite high-pressure pipe is improved, particularly when a polyolefin-based resin having low creep performance is used as the resin forming the inner layer The stretched polyolefin resin sheet is preferably crosslinked.

The stretched polyolefin resin sheet is obtained by stretching a polyolefin resin sheet processed into a sheet shape. The means for producing the polyolefin resin sheet is not particularly limited, but examples thereof include extrusion molding by the T-die method and roll molding by the calender method.

The means for continuously stretching the polyolefin resin sheet is not particularly limited,
For example, a method of stretching a heated polyolefin-based resin sheet between rolls of different speeds, a heated polyolefin-based resin sheet is sandwiched between rolls that rotate in mutually different directions, and the longitudinal direction of the pipe is reduced while reducing the thickness. The so-called rolling method, etc., in which the material is stretched to

These methods may be carried out only once in one method, or may be carried out stepwise more than once. When the stretching step is performed twice or more, a combination of a plurality of stretching methods may be performed.
In particular, when a relatively thick polyolefin-based resin sheet is stretched, it is preferable to perform the above-mentioned rolling and then the stretching.

The thickness of the polyolefin-based resin sheet (stretched raw fabric) before stretching is determined according to the intended use of the resulting composite high-pressure tube and the stretching ratio, and is not particularly limited, but is 0. It is preferably about 5 to 15 mm. When the thickness of the sheet is less than 0.5 mm, the thickness of the stretched polyolefin-based resin sheet becomes too thin, so that the handleability in the laminating work in the next step is reduced and the work becomes difficult to perform. If the thickness of the sheet exceeds 15 mm, the stretching load becomes too large, which may not only unnecessarily increase the stretching apparatus but also make the stretching operation difficult.

The stretched polyolefin resin sheet obtained from such a stretched raw fabric has a thickness of 50 to 1000 μm.
It will be about.

The width of the reinforcing layer made of a stretched polyolefin-based resin sheet depends on the diameter of the composite high-pressure pipe, the winding angle of the sheet,
It is appropriately selected depending on the winding method described later, and is not particularly limited. When a reinforcing layer having a relatively narrow width is used, a wide sheet may be slit and used in a required width.

The stretch ratio of the stretched polyolefin resin sheet is determined according to the properties of the crystalline polyolefin resin used and is not particularly limited, but preferably 10 in the longitudinal direction.
It is preferable that the film is stretched at least twice, more preferably at least 20 times. If the stretching ratio of the stretched polyolefin-based resin sheet in the longitudinal direction is less than 10 times, it may be difficult to obtain required strength and elastic modulus. Further, when the stretching in the width direction is performed, stretching in the longitudinal direction is suppressed, and it may be difficult to stretch 10 times or more in the longitudinal direction.

The stretched polyolefin-based resin sheet may be subjected to a surface treatment by a physical or chemical means, if necessary, for the purpose of improving its adhesiveness. For the surface treatment, for example, a physical surface treatment method for forming fine irregularities on the surface of the stretched polyolefin-based resin sheet by an embossing means such as sandblasting or a local heating means for the surface portion is used for the reason of workability and the like. Is preferred.

There is also a method of improving the adhesiveness by previously laminating an adhesive sheet on the surface of the stretched polyolefin resin sheet. Examples of the adhesive sheet include linear low density polyethylene, modified polyethylene, ethylene-vinyl acetate copolymer and the like.

Next, the inner layer and the outer layer of the composite high pressure pipe will be described.

In the composite high-pressure pipe to which the connection method of the present invention is applied, the inner layer is for passing the transport medium. Therefore, the type of synthetic resin used for the inner layer is appropriately selected according to the type of transport medium. Specific examples thereof include polyolefin resins such as high-density polyethylene, polyvinyl chloride, polyamide, various rubbers, and polyolefin elastomers, but are not particularly limited.

The thickness of the inner layer depends on the type of transport medium,
It is appropriately selected depending on the internal pressure used or the application. In addition,
Considering the fragments of the composite high-pressure pipe generated during manufacturing and the recycling of the used composite high-pressure pipe, the synthetic resin forming the inner layer is preferably a polyolefin resin.

In the composite high-pressure pipe to which the connection method of the present invention is applied, the outer layer is formed for the purpose of protecting the pipe surface and improving weather resistance. The resin that constitutes the outer layer,
The same synthetic resin as the above-mentioned inner layer can be used, and further, polyamide, acrylic resin, polyester resin or the like can be used. The synthetic resin used for the outer layer is used for
It is appropriately selected depending on the usage situation.

The wall thickness of the outer layer is appropriately selected depending on the type of the transport medium, the internal pressure used, or the application, like the inner layer. In addition, the fragments of the composite high-pressure pipe generated during manufacturing,
Considering recycling of the used composite high-pressure pipe, the synthetic resin forming the outer layer is preferably a polyolefin resin.

In the composite high-pressure pipe to which the connection method of the present invention is applied, the reinforcing layer includes a first reinforcing layer made of a stretched polyolefin resin sheet wound around the outer peripheral surface of the inner layer in an inclined circumferential direction, and in the axial direction of the tube. On the other hand, there may be mentioned one provided with a second reinforcing layer made of a stretched polyolefin resin sheet laminated so as to form a symmetric angle with the first reinforcing layer. By forming a reinforcing layer composed of a plurality of layers in this way, a composite high-pressure pipe having a higher pressure resistance than a synthetic resin pipe can be obtained. The inclined circumferential direction means that the sheet winding direction is inclined by a predetermined angle with respect to the tube axis direction.

The number of reinforcing layers is appropriately selected depending on the thickness of the sheet, the draw ratio, the performance required for the composite high-pressure tube, and the like, but the reinforcing layers having different draw ratios and thicknesses may be used.

Further, it is preferable that the reinforcing layers are laminated without any gap. By making the sheet width the same as the outer circumference of the cross-sectional shape of the composite high-pressure pipe, it is possible to perform lamination without any gap, but it is also possible for layers to be laminated with a slight gap.

The cross-sectional shape of the composite high-pressure pipe is not particularly limited, but a circular cross-section with a high efficiency of internal pressure strength and external force strength against weight, or a substantially square cross-section with rounded corners (corners) is preferable. With a complicated cross-sectional shape, it becomes difficult to stack the reinforcing layers.

The method for producing the composite high-pressure pipe to which the present invention is applied is not particularly limited, but for example, a polyolefin resin pipe such as a high-density polyethylene pipe as an inner layer is produced in a previous step and reinforced. A method of laminating the layer and the outer layer on the surface of the resin pipe can be mentioned.

As a method for obtaining a hollow inner layer,
The extrusion molding method used in the manufacture of pipes and hoses may be adopted. As a method for coating the outer layer, a method of extrusion coating using an extruder and a coating mold, or a sheet-shaped or tube-shaped outer layer is preliminarily molded and laminated on the outer surface of the reinforcing layer made of a stretched polyolefin-based resin sheet. There is a method of doing.

<Operation> According to the connection method of the present invention, the end portions of each composite high-pressure pipe are heated and melted, and the end portions of each composite high-pressure pipe are pressed against each other at a pressure higher than that of normal butt fusion. (For example, 0.15 MPa), the molten resin at the end of the inner layer is allowed to flow outward through the stretched polyolefin-based resin sheet at the butted portion.
A bead of molten resin at the inner layer end is formed on both the inside and the outside of the butt fusion-bonded portion. As a result, the composite high pressure pipes are firmly connected to each other.

Therefore, by applying the connecting method of the present invention to the connection of a water supply pipe or the like through which a high-pressure flow passes, the connecting portion of the composite high-pressure pipe is damaged, or water leaks at the connecting portion. There is no fear of.

In the connection method of the present invention, when connecting the composite high-pressure pipes whose inner layers are formed of high-density polyethylene, the end of each composite high-pressure pipe is heated at a heating temperature of 210 to 260.
C., heating time: It is preferable to heat and melt under the conditions of 90 to 250 sec. When heating and melting are performed under such conditions, the amount of melting at the end of the inner layer (high-density polyethylene) (melting length from the end face of the composite high-pressure pipe) can be increased, and The amount of molten resin flowing from the outside to the outside can be increased.

Next, each condition during heating / melting and butt fusion will be described below.

In the method of connecting the composite high-pressure pipes of the present invention,
When the synthetic resin forming the inner layer is high-density polyethylene, the heating temperature during heating and melting is 210 to 260 ° C. When the heating temperature is less than 210 ° C, the desired amount of molten resin is obtained. This requires a long heating time, and when the heating temperature is higher than 260 ° C., the problem that the resin (high-density polyethylene) in the butt fusion portion is significantly deteriorated is avoided. A more preferable range of heating temperature is 235 to 250 ° C.

The heating time at the time of heating and fusing is determined by the heating temperature, but when the heating temperature is 210 to 260 ° C., 90 to 250 sec is suitable. Heating time 9
If the time is less than 0 sec, the amount of the molten resin at the end of the inner layer is too small to obtain the desired fusion strength. Further, if the heating time is longer than 250 sec, the time required for butt fusion will be long, which causes a problem of productivity.

More specific range of heating time is 200 to 250 sec when the heating temperature is 210 ° C.,
When the heating temperature is 235 to 260 ° C, 90 to 120
It is preferably in the range of sec.

Among these heating / melting conditions, it is particularly preferable to set the heating temperature to 235 ° C. and the heating time to 90 to 150 sec.

In the method of connecting the composite high-pressure pipes of the present invention,
The pressure applied during butt fusion is preferably 0.1 to 0.2 MPa. If the pressure applied during butt fusion is less than 0.1 MPa, the desired fusion strength cannot be obtained. Further, if the applied pressure is larger than 0.2 MPa, there is a possibility of joining at the unmelted portion of the inner layer end portion, and stable fusion strength cannot be obtained.

[0054]

BEST MODE FOR CARRYING OUT THE INVENTION First, an example of a composite high-pressure pipe to which the connecting method of the present invention is applied will be described with reference to FIG.

The composite high-pressure pipe 1 shown in FIG. 1 is formed by spirally winding an inner layer 11 made of high-density polyethylene formed in a tubular shape, and a stretched polyethylene sheet 12a on the outer peripheral surface of the inner layer 11. Reinforcing layer 12 and the reinforcing layer 12
The outer layer 13 made of high-density polyethylene is laminated on the upper layer.

The reinforcing layer 12 laminated on the inner layer 11 is a stretched polyethylene sheet 12a in the form of a strip having an appropriate width dimension.
Is spirally wound at an inclination angle of 30 ° to 90 ° with respect to the tube axis of the inner layer 11, and the stretched polyethylene sheet 12a is further spirally wound thereon so that the inclination angle is opposite. It has a wound two-layer structure.

In the composite high-pressure pipe 1 having such a structure, a reinforcing layer 12 formed by spirally winding a stretched polyethylene sheet 12a having excellent tensile strength is laminated on an inner layer 11 made of high-density polyethylene. Therefore, the inner layer 11 is reinforced by the reinforcing layer 12. Therefore, the composite high-pressure pipe 1
It has excellent pressure resistance, and there is no risk of damage even if a high-pressure fluid flows inside the inner layer 11.

An example of connecting the composite high-pressure pipes 1 and 1 having the above-described configurations will be described together with a comparative example.

Example 1 [Heating and Melting Step] The composite high-pressure pipe shown in FIG. 1, that is, the inner layer 11 made of high-density polyethylene and the stretched polyethylene sheet 1
2a reinforcement layer 12 and high-density polyethylene outer layer 1
A composite high-pressure pipe (nominal diameter: 100 A) 1 composed of 3 is mounted on a fusion machine or the like (not shown), and as shown in FIG. 2, the end faces of 1, 1 of the composite high-pressure pipe are heated. The heating plates 2 are brought into contact with each other to heat the ends of the composite high-pressure pipes 1 and 1.

At this time, the composite high pressure pipes 1, 1 are not particularly pressed against the heating plate 2, and the end portion of the inner layer 11 of each composite high pressure pipe 1, 1 has a predetermined length. Heat until melted. The heating and melting conditions of the tube end are as follows: heating temperature 235 ° C., heating time 120 sec
c, and the length of the melted portion of the inner layer 11 (length from the tube end face) is 6.0 mm (1.2 times the wall thickness of the inner layer 11).

[But-joining process] Each composite high-pressure pipe 1,
When the end portion of 1 is heated to a molten state, the heating plate 2 is removed, and the end surfaces of the composite high-pressure pipes 1 and 1 are butted against each other with a pressing force of 0.15 MPa. With this match,
As shown in FIG. 3, the inner layers 11, 1 of the respective composite high-pressure pipes 1, 1
Molten resin at one end is extruded toward the outside,
It flows between the reinforcing layers 12 and 12 and flows to the outside of the pipe. The fluidized resin (molten resin) is eluted outside the pipe, and is curled toward the outside to be pressed against each other. As a result, the inner layers 11, 11 of the composite high-pressure pipes 1, 1 are fused to each other.

FIG. 4 shows the state of the connection portion J fusion-bonded. At the connecting portion J of the composite high-pressure pipes 1 and 1, a thick bead B is formed over the entire circumference by the inner layers 11 and 11 fused to each other, and the composite high-pressure pipes 1 and 1 are firmly connected to each other. It is joined.

Therefore, when the composite high-pressure pipe 1 is installed as a water supply pipe or the like through which a high-pressure flow passes, the connecting method of the present invention is applied to fusion-bond the composite high-pressure pipes 1 and 1 together. By doing so, the joint portion is firmly connected over the entire circumference, so there is no risk of damage or water leakage at the connection portion J.

In Example 1 above, the inner layer 11 and the reinforcing layer 1 were used.
Although an example in which the composite high-pressure pipe 1 composed of three layers of 2 and the outer layer 13 is connected has been shown, when the composite high-pressure pipe has a two-layer structure of the inner layer 11 and the reinforcing layer 12, melting and heating under the same conditions as above. The butt fusion may be performed to connect the composite high pressure pipes.

<Comparative Example 1> Composite high-pressure pipe (nominal diameter: 100)
The heating / melting conditions of the pipe end portion of A) are normal conditions: heating temperature 250 ° C., heating time 90 sec, the length of the molten portion of the inner layer 11 (length from the pipe end face) is 5.5 mm, and the pressure is applied. After connecting at a pressure of 0.075 MPa in the same manner as in Example 1, the joint was reinforced with a reactive resin.

<Performance Evaluation Test> The composite high-pressure pipes connected in Example 1 and Comparative Example 1 were tested for the following items to evaluate their performance.

(A) A 1000 mm tube body (including the connecting portion) was cut out from the composite high-pressure pipe to which the flat water pressure test connection was performed, and as shown in FIG. At the same time as pressurizing 0.0 MPa, the joint was sandwiched between the flat pressure plates 3 and flattened by 50% at the maximum. The test results are shown in Table 1.

(B) Bending Water Pressure Resistance Test A 1500 mm tube body (including the connection part) was cut out from the composite high-pressure tube to which the connection was made, and as shown in FIG. At the same time as 2.0 MPa was applied, a bending load was applied to the joint by the bending evaluation jig 6 and the joint was bent at a maximum of 30 °. The test results are shown in Table 1.

[0069]

[Table 1]

As is clear from the results shown in Table 1, the joint portion of the composite high-pressure pipe which has been subjected to the connecting method of the present invention is excellent in flexibility, and even if excessive force acts on the joint portion due to an earthquake or the like, the joint portion is It was confirmed that it would not be destroyed. On the other hand, in Comparative Example 1, since the reactive resin was hard, when it was flattened, the reinforcing layer of the reactive resin broke, and thereafter the joint portion broke. Also, in the bending water pressure resistance test, the joint was broken when excessive bending acted at the same time. Furthermore, it was confirmed that in the working process, the time required for Example 1 was significantly shorter than that for Comparative Example 1.

[0071]

As described above, according to the method of connecting the composite high-pressure pipes of the present invention, the end portions of the composite high-pressure pipes are normally heated and melted, and the end portions of the composite high-pressure pipes are normally connected to each other. Since the molten resin at the end of the inner layer is abutted with a pressure so that the molten resin at the end of the inner layer flows outwardly through the stretched polyolefin resin sheets at the butted portion, the molten inner layer resin will spread over the entire circumference of the pipe. It is firmly joined and the pressure resistance of the connection part is equal to or higher than that of the original pipe. Thereby, the step of reinforcing the connecting portion with resin after connecting the composite high-pressure pipes can be omitted, and the workability is improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a composite high-pressure pipe to which a connection method of the present invention is applied.

FIG. 2 is an explanatory diagram of an embodiment of a connection method of the present invention.

FIG. 3 is an explanatory diagram of the same embodiment.

FIG. 4 is a diagram showing a structure of a connecting portion of a composite high-pressure pipe to which a connection is made in the embodiment of the present invention.

FIG. 5 is a diagram schematically showing a schematic configuration of a measuring device used for a performance evaluation test in the connection method of the present invention.

FIG. 6 is a diagram schematically showing a schematic configuration of a measuring device used for a performance evaluation test in the connection method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Composite high-pressure pipe 11 Inner layer (made of high-density polyethylene resin) 12 Reinforcing layer 12a Stretched polyethylene sheet (stretched polyolefin-based resin sheet) 13 Outer layer 2 Heating plate 3 Flat pressure plate 4 Water pressure jig 5 Pressurizing pump 6 Bending evaluation jig Ingredient

Claims (6)

[Claims] 1. An inner layer made of a synthetic resin formed into a tubular shape,
Ends of a composite high-pressure pipe having a reinforcing layer formed by spirally winding a stretched polyolefin-based resin sheet on the outer peripheral surface of the inner layer, and a synthetic resin outer layer laminated on the reinforcing layer. A method of butt connection, in which the end of each composite high-pressure pipe is heated and melted, the end of each composite high-pressure pipe is passed through the stretched polyolefin-based resin sheet at the abutting part A method for connecting a composite high-pressure pipe, characterized in that the ends of the inner layer are fused by abutting with a pressing force that flows outward. 2. The method for connecting a composite high-pressure pipe according to claim 1, wherein when connecting the composite high-pressure pipe whose inner layer is formed of high-density polyethylene, the end of each composite high-pressure pipe is heated at a heating temperature of 210 to 210. 260 ° C, heating time: 90 to 250se
A method for connecting a composite high-pressure pipe, which comprises heating and melting under the condition c. 3. The method for connecting a composite high-pressure pipe according to claim 1 or 2, wherein the end portions of the composite high-pressure pipe are 0.1 to
A method for connecting a composite high-pressure pipe, which comprises butt-fusing with a pressure of 0.2 MPa. 4. A synthetic resin inner layer formed into a tubular shape,
A method for butt-connecting the ends of a composite high-pressure pipe having a reinforcing layer formed by spirally winding an expanded polyolefin-based resin sheet on the outer peripheral surface of the inner layer, wherein the end of each composite high-pressure pipe is connected. While the parts are heated and melted, the ends of the composite high-pressure pipes are butted against each other with a pressing force such that the molten resin at the inner layer ends flows outward through the stretched polyolefin-based resin sheets at the butted parts. And a method for connecting a composite high-pressure pipe, characterized in that the ends of the inner layer are fused together. 5. The method of connecting composite high-pressure pipes according to claim 4, wherein when connecting the composite high-pressure pipes whose inner layers are formed of high-density polyethylene, the end of each composite high-pressure pipe is heated at a heating temperature of 210 to 210. 260 ° C, heating time: 90 to 250se
A method for connecting a composite high-pressure pipe, which comprises heating and melting under the condition c. 6. The method of connecting a composite high-pressure pipe according to claim 4 or 5, wherein the end portions of the composite high-pressure pipe are connected to each other by 0.1 to
A method for connecting a composite high-pressure pipe, which comprises butt-fusing with a pressure of 0.2 MPa.